Abstract:An analytical method for the determination of trace acid-soluble boron in structure steel for ship and ocean engineering by inductively coupled plasma optical emission spectrometry was developed. The effects of sample digestion vessels, inorganic acids, and instrumental parameters, including radio frequency power, nebulizer pressure, auxiliary gas flow rate, and pump speed, on the determination of boron were investigated. The optimal analytical spectral line was selected, and the background interference from the iron matrix and coexisting ions were discussed. The optimal working conditions were determined as follows: radio frequency power of 1.15 kW, nebulizer pressure of 0.18 MPa, auxiliary gas flow rate of 0.5 L/min, and a pump speed of 100 rpm. A 0.500 g sample was weighed into a quartz vessel and digested with 1 mL of water, 9 mL of hydrochloric acid, and 3 mL of nitric acid by heating to prepare the test solution. The B 182.64 nm spectral line was selected for analysis, with 182.58 nm and 208.96 nm as alternatives. A matrix-matching method was employed to eliminate background interference, and a series of calibration curves were established using an iron matrix solution, achieving a linear correlation coefficient of 0.999. Through inter-laboratory collaborative study, the limit of quantification (LOQ) of the method was found to be 0.0002%–0.0005%. The results for steel standard reference materials were in good agreement with their certified values. At a 95% confidence level, the repeatability limits (r) for the four concentration levels of 0.001%, 0.004%, 0.0125%, and 0.150% were 0.00026%, 0.00076%, 0.0019%, and 0.0151%, respectively, while the reproducibility limits (R) were 0.00053%, 0.00096%, 0.0020%, and 0.0232%, respectively. The precision of the method was generally comparable to that of the classical methanol distillation-curcumin photometric method.